The thrips Megalurothrips usitatus Bagnall and Frankliniella intonsa Trybom (Thysanoptera: Thripidae) are important pests in cowpea-growing areas of south China. Parthenogenesis is an important reproductive form of thysanopterans, and plays an important role in maintaining population growth. To understand the developmental and reproductive characteristics of these 2 thrips species during parthenogenesis, we compared the age-stage life tables of M. usitatus and F. intonsa on cowpea pods under natural regimes during the summer and winter. The results showed that the total preadult period and total preoviposition period of M. usitatus were significantly longer than those of F. intonsa in both seasons. Moreover, longevity of adult M. usitatus (29.53 days) was shorter compared with adult F. intonsa (34.00 days) in summer, whereas higher fecundity (220.8 eggs/female) and more oviposition days (37.83 days) were observed in M. usitatus compared with F. intonsa in winter (fecundity = 179.83 eggs/female, oviposition days = 33.03 days). The net and gross reproductive rates of M. usitatus were significantly greater than those of F. intonsa during winter. In addition, the intrinsic and finite rates of increase of M. usitatus were significantly lower than those of F. intonsa, and the mean generation time of M. usitatus was significantly longer than that of F. intonsa both in summer and winter. These results indicated that parthenogenesis has species specificity among thrips, which in turn affects population development, especially under changing environments.

AbstractDifferent reproductive modes are characterized by costs and benefits that depend on ecological contexts. For example, sex can provide benefits under complex biotic interactions, while its costs increase under mate limitation. Furthermore, ecological contexts often vary along abiotic gradients. Here, we study how these factors simultaneously influence the frequency of sex in the facultatively parthenogenetic mayfly Alainites muticus. We first verified that parthenogenesis translates into female-biased population sex ratios. We then measured the density of individuals (a proxy for mate limitation) and community diversity (biotic interaction complexity) for 159 A. muticus populations covering a broad altitudinal gradient and used structural equation modeling to investigate their direct and indirect influences on sex ratios. We found no effect of community diversity or altitude on sex ratios. Furthermore, even when females can reproduce parthenogenetically, they generally reproduce sexually, indicating that the benefits of sex exceed its costs in most situations. Sex ratios become female-biased only under low population densities, as expected if mate limitation was the main factor selecting for parthenogenesis. Mate limitation might be widespread in mayflies because of their short adult life span and limited dispersal, which can generate strong selection for reproductive assurance and may provide a stepping stone toward obligate parthenogenesis.

Scytosiphon is a common intertidal genus widely distributed on temperate coasts worldwide. Recently, eight species have been delimited with molecular tools. Although S. lomentaria is the only species that predominates in the macroalgal literature of the Southwestern Atlantic Ocean (SwAO), unpublished molecular data obtained for a population study of S. lomentaria revealed hidden species diversity of Scytosiphon among the individuals collected from four localities at the SwAO. The aim of this study was to revise the identity and phylogenetic relationships of Scytosiphon from temperate coasts of the SwAO using DNA data. Thalli were collected from the Argentinean coast between 39° S and 43° S, from which cox1 and rbcL gene sequences were obtained. Phylogenies and haplotype networks were inferred and morphology of gametophytes was studied. Four species were recognized, S. lomentaria, S. promiscuus, S. shibazakiorum, and one species that belongs to a complex of species known as \"Scytosiphon Atlantic complex.\" This complex was known to occur only in the North Atlantic, however, the results found in this study revealed that it has an extended distribution range that includes the southern hemisphere, where its populations have high genetic diversity and unique haplotypes. The morphological differences among the four species were subtle; denoting that previous Scytosiphon records from the SwAO attributed to the renowned S. lomentaria could represent different species. In addition, sex ratio and genome-wide single nucleotide polymorphisms (SNPs) analyses were done for populations of S. promiscuus presumably introduced to the SwAO, and the results indicated that they included female-dominant parthenogenetic populations, which were probably introduced from Japan.

Obligate parthenogenesis is found in only 0.1% of the vertebrate species, is thought to be relatively short lived and is typically of hybrid origin. However, neither the evolutionary persistence of asexuality in vertebrates, nor the conditions that allow the generation of new parthenogenetic lineages are currently well understood. It has been proposed that vertebrate parthenogenetic lineages arise from hybridisation between two divergent taxa within a specific range of phylogenetic distances (the \'Balance Hypothesis\'). Moreover, parthenogenetic species often maintain a certain level of hybridisation with their closest sexual relatives, potentially generating new polyploid hybrid lineages. Here we address the role of hybridisation in the origin and evolutionary lifespan of vertebrate parthenogens. We use a set of microsatellite markers to characterise the origins of parthenogens in the lizard genus Darevskia, to study the distinctiveness of sexual and asexual taxa currently in sympatry, and to analyse the evolutionary consequences of interspecific hybridisation between asexual females and sexual males. We find that parthenogens result from multiple past hybridisation events between species from specific lineages over a range of phylogenetic distances. This suggests that the Balance Hypothesis needs to allow for lineage-specific effects, as envisaged in the Phylogenetic Constraint Hypothesis. Our results show recurrent backcrossing between sexual and parthenogenic Darevskia but neither gene flow nor formation of new asexual lineages. We suggest that, along with their demographic advantage, parthenogens gain additional leverage to outcompete sexuals in nature when the retention of sexual reproductive machinery allows backcrossing with their sexual ancestors.

The preimplantation development of mammals generally follows the same plan. It starts with the formation of a totipotent zygote, and through consecutive cleavage divisions and differentiation events leads to blastocyst formation. However, the intervening events may differ between species. The regulation of these processes has been extensively studied in the mouse, which displays some unique features among eutherian mammals. Farm animals such as pigs, cattle, sheep and rabbits share several similarities with one another, and with the human developmental plan. These include the timing of epigenetic reprogramming, the moment of embryonic genome activation and the developmental time-frame. Recently, efficient techniques for genetic modification have been established for large domestic animals. Genome sequences and gene manipulation tools are now available for cattle, pigs, sheep and goats, and a larger number of genetically engineered livestock is now accessible for biomedical research. Yet, these animals still make up less than 0.5% of animals in research, mainly due to our inadequate knowledge of the processes responsible for pluripotency maintenance (to date no stable naïve embryonic stem cell lines have been established) and early development. In this review, we highlight our present knowledge of the key preimplantation events in the 3 non-rodent species which present the highest potential for biomedical research related to early embryonic development: cattle, which offer an excellent model to study human in vitro embryo development, pigs which emerge as models to study the long-term effects of gene-based therapies and rabbits, which in many aspects of embryology resemble the human.

Successive generations of bi- and multivoltine species encounter differing biotic and abiotic environments intra-annually. The question of whether selection can independently adjust the relationship between body size and components of reproductive effort within successive generations in response to generation-specific environmental variation is applicable to a diversity of taxa. Herein, we develop a conceptual framework that illustrates increasingly independent life history adjustments between successive generations of taxa exhibiting complex life cycles. We apply this framework to the reproductive biology of the gall-forming insect, Belonocnema treatae (Hymenoptera: Cynipidae). This bivoltine species expresses cyclical parthenogenesis in which alternating sexual and asexual generations develop in different seasons and different environments. We tested the hypotheses that ecological divergence between the alternate generations is accompanied by generational differences in body size, egg size, and egg number and by changes in the relationships between body size and these components of reproductive effort. Increased potential reproductive effort of sexual generation B. treatae is attained by increased body size and egg number (with no trade-off between egg number and egg size) and by a significant increase in the slope of the relationship between body size and potential fecundity. These generation-specific relationships, interpreted in the context of the model framework, suggest that within each generation selection has independently molded the relationships relating body size to potential fecundity and potential reproductive effort in B. treatae. The conceptual framework is broadly applicable to comparisons involving the alternating generations of bi- and multivoltine species.

Embryonic stem cell (ESC) derivatives hold great promise for the construction of tissue-engineered skin equivalents (TESE). However, harvesting of ESCs destroys viable embryos and may lead to political and ethical concerns over their application. In the current study, we directed mouse parthenogenetic embryonic stem cells (pESCs) to differentiate into fibroblasts, constructed TESE, and evaluated its function in vivo.
The stemness marker expression and the pluripotent differentiation ability of pESCs were tested. After embryoid body (EB) formation and adherence culture, mesenchymal stem cells (MSCs) were enriched and directed to differentiate into fibroblastic lineage. Characteristics of derived fibroblasts were assessed by quantitative real-time PCR and ELISA. Functional ability of the constructed TESE was tested by a mouse skin defects repair model.
Mouse pESCs expressed stemness marker and could form teratoma containing three germ layers. MSCs could be enriched from outgrowths of EBs and directed to differentiate into fibroblastic lineage. These cells express a high level of growth factors including FGF, EGF, VEGF, TGF, PDGF, and IGF1, similar to those of ESC-derived fibroblasts and mouse fibroblasts. Seeded into collagen gels, the fibroblasts derived from pESCs could form TESE. Mouse skin defects could be successfully repaired 15 days after transplantation of TESE constructed by fibroblasts derived from pESCs.
pESCs could be induced to differentiate into fibroblastic lineage, which could be applied to the construction of TESE and skin defect repair. Particularly, pESC derivatives avoid the limitations of political and ethical concerns, and provide a promising source for regenerative medicine.

BACKGROUND: Many patients with dermatitis over photo-exposed body areas are positive to many contact allergens and have a pre-existing allergic contact dermatitis.
METHODS: This study included patients who presented to a tertiary centre in India with dermatitis on photo-exposed body areas suspected of chronic actinic dermatitis. Their detailed histories were recorded and cutaneous and systemic examinations were performed. Patch testing was done in all the patients and photo-patch testing was carried out in 86 patients.
RESULTS: Altogether 101 patients were included (69 males, 32 females). The most common presentation was lichenified hyperpigmented plaques on the photo-exposed sites. Photosensitivity was recorded in 64 (63%) patients and summer exacerbation in 52 (52%). Exposure to the Parthenium hysterophorus weed was recorded in 70 (69%) patients, 27 (26.7%) had a history of hair dye application and 20 (20%) had a history of atopy. Photo-patch test was positive in 11 (12.8%) patients and patch testing was positive in 71 (70%). Parthenium hysterophorus was the most common allergen implicated and was positive in three (4%) photo-patch and 52 (52%) patch tests. Other positive photo-patch test allergens were perfume mix, balsam of Peru, thiuram mix, Compositae mix and promethazine hydrochloride. Other common patch test allergens were parthenolide, colophony, fragrance mix and p-phenylenediamine (PPD) base.
CONCLUSIONS: In the Indian population parthenium and perfume mix are the most common photoallergens in patients with dermatitis over photo-exposed areas, while parthenium, colophony, fragrance mix and PPD are the common positive allergens.

The ultrastructure of the ovary of Fasciola hepatica collected from field-infected sheep, was compared with that of flukes from laboratory-infected rats harbouring the Oberon or the Cullompton fluke isolate. At the periphery of the ovarian tubules, in all flukes, interstitial tissue was identified that appears to provide physical support and facilitate the metabolism of the germinal-line cells. Oogonia undergo mitotic division to maintain the cell population and to produce oocytes. Early oocytes feature conspicuous synaptonemal complexes in the nucleoplasm, and these become less evident as the oocytes grow in size, move towards the core of the ovarian tubule, and synthesise osmiophilic bodies. The latter may represent cortical granules, and serve to block polyspermy. The identity of the synaptonemal complexes was confirmed by immunocytochemical labelling of synaptonemal proteins. The occurrence of synaptonemal complexes in the oocytes of all fluke types examined indicates that pairing of bivalent chromosomes, with the potential for genetic recombination and chiasmata formation, is a feature of the triploid aspermic parthenogenetic Cullompton flukes, as well as of the wild-type out-breeding field-derived and Oberon isolate flukes. In oocytes within shelled eggs in the proximal uterus of all flukes, condensed chromosomes align at meiotic metaphase plates. Following the reduction division, two equal pronuclei appear in each oocyte in the distal uterus. On the basis of these observations, a mechanism of facultative parthenogenesis for F. hepatica is proposed that accommodates the survival and clonal expansion of triploid aspermic isolates.

BACKGROUND: Azathioprine in daily doses has been shown to be effective and safe in the treatment of Parthenium dermatitis. Weekly pulses of azathioprine (WAP) are also effective, but there are no reports comparing the effectiveness and safety of these two regimens in this condition.
OBJECTIVE: To study the efficacy and safety of WAP and daily azathioprine in Parthenium dermatitis.
METHODS: Sixty patients with Parthenium dermatitis were randomly assigned to treatment with azathioprine 300 mg weekly pulse or azathioprine 100 mg daily for 6 months. Patients were evaluated every month to assess the response to treatment and side effects.
RESULTS: The study included 32 patients in the weekly azathioprine group and 28 in the daily azathioprine group, of whom 25 and 22 patients respectively completed the study. Twenty-three (92%) patients on WAP and 21 (96%) on daily azathioprine had a good or excellent response. The mean pretreatment clinical severity score decreased from 26.4±14.5 to 4.7±5.1 in the WAP group, and from 36.1±18.1 to 5.7±6.0 in the daily azathioprine group, which was statistically significant and comparable (P=0.366). Patients on WAP had a higher incidence of adverse effects (P=0.02).
CONCLUSIONS: The study had a small sample size and the amount of clobetasol propionate used in each patient was not determined, though it may not have affected the study outcome due to its comparable use in both groups.
CONCLUSIONS: Azathioprine 300 mg weekly pulse and 100 mg daily dose are equally effective and safe in the treatment of Parthenium dermatitis.